//
// DTDHandler.h
//
// Library: XML
// Package: SAX
// Module:  SAX
//
// SAX DTDHandler Interface.
//
// Copyright (c) 2004-2006, Applied Informatics Software Engineering GmbH.
// and Contributors.
//
// SPDX-License-Identifier:	BSL-1.0
//


#ifndef SAX_DTDHandler_INCLUDED
#define SAX_DTDHandler_INCLUDED


#include "Poco/XML/XML.h"
#include "Poco/XML/XMLString.h"


namespace Poco
{
namespace XML
{


    class XML_API DTDHandler
    /// If a SAX application needs information about notations and unparsed entities,
    /// then the application implements this interface and registers an instance with the
    /// SAX parser using the parser's setDTDHandler method. The parser uses the instance
    /// to report notation and unparsed entity declarations to the application.
    ///
    /// Note that this interface includes only those DTD events that the XML recommendation
    /// requires processors to report: notation and unparsed entity declarations.
    ///
    /// The SAX parser may report these events in any order, regardless of the order in
    /// which the notations and unparsed entities were declared; however, all DTD events
    /// must be reported after the document handler's startDocument event, and before the first
    /// startElement event. (If the LexicalHandler is used, these events must also be reported before the endDTD event.)
    ///
    /// It is up to the application to store the information for future use (perhaps in a hash table or
    /// object tree). If the application encounters attributes of type "NOTATION", "ENTITY", or "ENTITIES",
    /// it can use the information that it obtained through this interface to find the entity and/or notation
    /// corresponding with the attribute value.
    {
    public:
        virtual void notationDecl(const XMLString & name, const XMLString * publicId, const XMLString * systemId) = 0;
        /// Receive notification of a notation declaration event.
        ///
        /// It is up to the application to record the notation for later reference,
        /// if necessary; notations may appear as attribute values and in unparsed
        /// entity declarations, and are sometime used with processing instruction
        /// target names.
        ///
        /// At least one of publicId and systemId must be non-null. If a system identifier
        /// is present, and it is a URL, the SAX parser must resolve it fully before passing
        /// it to the application through this event.
        ///
        /// There is no guarantee that the notation declaration will be reported before any
        /// unparsed entities that use it.
        ///
        /// Note that publicId and systemId maybe null, therefore we pass a pointer rather than a reference.

        virtual void
        unparsedEntityDecl(const XMLString & name, const XMLString * publicId, const XMLString & systemId, const XMLString & notationName)
            = 0;
        /// Receive notification of an unparsed entity declaration event.
        ///
        /// Note that the notation name corresponds to a notation reported by the
        /// notationDecl event. It is up to the application to record the entity for
        /// later reference, if necessary; unparsed entities may appear as attribute values.
        ///
        /// If the system identifier is a URL, the parser must resolve it fully before
        /// passing it to the application.
        ///
        /// Note that publicId maybe null, therefore we pass a pointer rather than a reference.

    protected:
        virtual ~DTDHandler();
    };


}
} // namespace Poco::XML


#endif // SAX_DTDHandler_INCLUDED
